The floors of theater stages have floor sections that can be lowered and displaced and serve the purpose of exposing openings in the stage floor in order to permit persons, objects, etc., to disappear or appear at this point. Such floor sections, also called trap doors, which are integrated within the stage, flush with the floor, are displaced, individually or in groups, on rail-like guides by means of rollers or skids in a coordinated manner. According to a more recent suggestion, the traveling stage floor section is mounted to one side on the stage structure and is swiveled for opening and closing by means of an actuating member, which acts on the underside of the movable section.
For appearances from below or exits from above, lowerable platforms, so-called elevating platforms, on which persons or the like are raised to the stage level or lowered to the level of the stage basement, are positioned under the stage floor opening provided.
Lifting devices for elevating platforms, which are designed according to the principle of the forklift, are known. In these designs, it is necessary to build up an additional scissors-like structure to bridge over the distance between the maximum lifting heiqht and the stage level. The shears or scissor-like elements can be extended and retracted manually or by means of a motor drive. The floor of the lowering platform has a defined area, to which the traveling carriage of the device is adapted.
It is therefore necessary to provide a plurality of lowering devices with platforms of corresponding area dimensions for stage floor openings of different sizes.
As a consequence of the measures resulting from the design principle, such lowering systems weigh about 1 ton in the case of platform sizes of approximately 1.times.1m and a payload of approximately 2,000 Newton. This weight causes difficulties in terms of the handling of the device.